this is again my error messages not telling the whole story, ill see if i can
get the term "foreign_keys" back in there:
mapper(Sensor, sensors,
properties={
'data': relationship(Data, backref='sensor',
foreign_keys=[data.c.id_meas],
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
or
mapper(Sensor, sensors,
properties={
'data': relationship(Data, backref='sensor',
foreign_keys=[sensors.id_meas],
primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
data.c.id_acq==acquisitions.c.id,
acquisitions.c.id_cu==sensors.c.id_cu),
cascade='all, delete-orphan', single_parent=True)
})
depending on if this is one-to-many or many-to-one. A relationship like this
is really better off as a viewonly=True since populating it is not going to add
rows to the "acquisitions" table.
On Dec 30, 2010, at 10:15 AM, neurino wrote:
> data = Table('data', metadata,
> Column('id', Integer, primary_key=True),
> Column('id_acq', Integer, ForeignKey('acquisitions.id'),
> nullable=False),
> Column('id_meas', Integer, nullable=False),
> Column('value', Float, nullable=True),
> )
>
> acquisitions = Table('acquisitions', metadata,
> Column('id', Integer, primary_key=True),
> Column('id_cu', Integer, ForeignKey('ctrl_units.id'),
> nullable=False),
> Column('datetime', DateTime, nullable=False),
> )
>
> sensors = Table('sensors', metadata,
> Column('id_cu', Integer, ForeignKey('ctrl_units.id'),
> primary_key=True,
> autoincrement=False),
> Column('id_meas', Integer, primary_key=True, autoincrement=False),
> Column('name', Unicode(20), nullable=False),
> Column('desc', Unicode(40), nullable=False),
> )
>
> ctrl_units = Table('ctrl_units', metadata,
> Column('id', Integer, primary_key=True, autoincrement=False),
> Column('desc', Unicode(40), nullable=False)
> )
>
> and this mapping:
>
> ...
> orm.mapper(Sensor, sensors,
> properties={
> 'data': orm.relationship(Data, backref='sensor',
> primaryjoin=and_(sensors.c.id_meas==data.c.id_meas,
> data.c.id_acq==acquisitions.c.id,
> acquisitions.c.id_cu==sensors.c.id_cu),
> cascade='all, delete-orphan', single_parent=True)
> })
> ...
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